Francis l



Feb. 2 1925. 1,571,900

F. L. LORD TUNED RADIO FREQUENCY RECEIVING SYSTEM Filed March 12, 1925 IIIIIIIIIIEEAIEV V is INVENTOR, K M,

BY M AW,

ATTORNEY.

Patented Feb. 2, 1926.

FRANCIS L. LORD, OF NEWARK, NEW JERSEY, ASSIGNOB OF 0NE-HALF TO HENRY J.

LUCKE, OF NEW YQBK, N. Y.

TUNED RADIOFREQUENCY RECEIVING SYSTEM.

Application filed March12, 1825. Serial No. 15,082.

To all whom it may concern:

Be it known that I, FRANCIS L. LORD, a citizen of the United States of America, residing at county of Essex, city of Newark, State of New Jersey, have invented certain new and useful Improvements in Tuned Radiofrequency Receiving Systems, of which the following is a specification.

This invention relates to improvements in tuned radio frequency receiving systems.

An object of this invention is to provide a radio receiving system preferably ofthe tuned radio frequency type whereby the efficiency of the set is maintained substantially for all wave lengths within the range of the receiving set.

Pursuant to a preferred form of my invention, the receiving system comprises one or more tuned radio frequency stages including a coupling between the antenna and the first radio frequency stage and a coupling between the detector stage and the radio frequency stage in advance thereof. The coupling for any stage comprises a primary member including a fixed COll and a rotary coil, said fixed coil and said rotary.

' coil being in inductive relation with the secondary. member, thus affording the proper adjustment of the rotary coil of the primary member relative to the secondary member for the respective settings of the variable condenser of the stage for the desired frequencies or wave lengths.

In the mostpreferred forms of the invention, the secondary member is mounted in close inductive relation with the fixed coil of the primary member and the rotary primary coil is adjusted in position relativerto the secondary coil and the fixed primary coil., Such rotary coil is preferably mounted on the shaft of the variable condenser of the particular stage and-the turns of the rotary primary coil are selected relative to the turns of the fixed primary coil to afford simultaneous setting of the variable condenser and the rotary primary coil for highest efficiency at the respective settings.

Further features and objects of the in vention will be more fully understood from the following detail description and the accompanying drawing, in which Fig. 1 is a diagram showing the circuit connections of more preferred form of my invention ,3

nected by the aerial conductor 2 to the terminal 3 of the coil 4:. The other terminal 5 of the coil 4 is connected by the lead 6 to the terminal 7 of the coil 8. The other terminal 9 of the coil 8 is connected by the conductor 10 through the junction point 11 to ground 12. The coil 4: and the coil 8 constitute the primary member of the cou pling 14; the secondary member in the form of a coil is indicated at 15. The coil 4: is preferably movably mounted, as in the form of a rotor coil and variable in setting as is indicated by the arrow 16.

The variable condenser 13 of the first radio frequency stage is preferably connect ed in parallel to the secondary coil 15 of the coupling 14.- The terminal 17 of the secondary coil 15 is connected by the lead 18, lead 19 to the junction point 11 and to ground 12 and also by the conductor 20 to the'negative terminal 21 of the A battery 22. The opposite terminal 28. of the secondary coil 15 is connected by the lead 24: to the grid electrode 25 of the audion tube 26 or equivalent. One terminal of the filament electrode 27 of the tube 26 is connected by the lead 28 to the negative terminal 21 of the Av battery 22 and the opposite terminal of the filament electrode 27 is connected through the variable resistance 29 to the positive terminal 30 of the A battery 22. The plate electrode 31 of the audion tube 26 is connected by the lead 32 through the coil 33 of the primary member of the coupling 34. The coil 35 of the primary of the coupling 84 is connected by the conductor 36 to the terminal 37 of the B battery 38." The primary coil 33 of the coupling 34 corresponds to the aforesaid primary coil 4 of the coupling 14 and the primary coil 35.

38 is connected by the lead 40, lead 41 to the negative terminal 21 of the A' battery 22 and therewith to the aforesaid parts connected to the negative terminal 21 of the A battery.

The secondary coil 42 of the coupling 34 is connected in the second radio frequency sta e on its one side, similarly to the aforesai secondary coil 15 of the coupling 14, by the conductors 43, 41 to the-negative terminal 21 of the A battery 22 and on its opposite side by the conductor 44 to the grid electrode 45 of the audion tube 46. The variable condenser 47 of the second radio frequency stage is connected in parallel to the secondary coil 39, similarly as the variable condenser 13 in the first radio frequency stage. The filament electrode 48 of the audion tube 45 is connected on its one side by the lead 49, lead 41 to the negative terminal 21 of the A battery 22 and on its other side by the lead 50 through the variable resistance 51, lead 52 to the positive termimail 30 of the A battery 22. The plate electrode 53 of the audion tube 46 is connected. through the lead 54 through the primary coil 55 of the coupling 56. The primary coil 55 corresponds to the aforesaid primary coils 33, 4 and is similarly connected With its rotor primary coil 57 corresponding to theaforesaid rotor primary coils 35, 8. The

rotor primary coil 57 is connected by the lead 58, lead 36 to the terminal 37 of the B battery 38.

The filament electrode 48 of the audion tube 46 is connected by its lead 49, lead 40 to the negative terminal 39 of the B battery 38.

The secondary coil 59 of the coupling 56 is connected on one side by the conductor 60, conductor 52, to the positive terminal 30 of the A battery 22 and on its opposite side by the conductor 61 to the grid electrode 62 of the audion tube 63 of the detector stage. The filament electrode 64 of the audion'63 is connected on one side by its conductor 65 to the conductor 66 leading to the negative terminal 21 of the A battery 22 and also to the negative terminal 29 of the B battery 38. The opposite side of the filament electrode 34 is connected through the variable resistance 66 to the positive terminal 30 of the A battery 22. The plate electrode'67 of the audion 63 is connected by the lead 68 through the primary 69 of the audio transformer 70, thence by the lead 71 to the terminal 72 of the B battery 38. The terminal 7 2 is preferably at 45 volts.

The variable condenser 73 is connected preferably in parallel to the secondary coil 59 of the detector stage.-

In attunin the aforesaid radio frequency stages and t e detector stage, the variable condensers 13, 47, 73 are set for the desired frequency and the rotor coils 4, 33, 55 are set for the highest etliciency for the respective stages.

Preferably, the rotor coil 8 is mounted on the shaft of the variable condenser 13 and the number of turns of the rotor coil 8 are selected relative to the number of turns of its fixed primary coil 4 to correspond simultaneously and arcuately to the settings of the condenser 13. In such arrangement, the primary rotor coil 8 is disposed concentrically Within the fixed primary coil 4 and the secondary coil 15, the fixed primary coil 4 surrounding said secondary coil 15 and in. close inductive relation.

In a similar manner, the primary rotor coil 35 is mounted on the shaft of the variable condenscr 47 of the second tuned radio frequency stage and the rotor'coil 57' simi larly mounted on the shaft of the variable condenser 73 of the detector stage.

The secondary 74 of the audio transformer is connected on its one side to the grid electrode 75 of the audion 76 and at its opposite side to the lead 77 running to the conductor 78, conductor 66 to the negative terminal 39 of the B battery 38 and also through the conductor 41 to the ue ative terminal 21 of the A battery 22." he filament electrode 7 9 of the audion? 6 is connected on one side by its conductor 80, conductor 7 8, conductor 41 to the negative terminal 21 of the A battery 22 and on its 01)- posite side through the variable resistance 81 to the conductor 82 to the positive terminal 30 of the A battery 22.-

The plate electrode 83 of the audion 76 is connected by the conductor 84 to one side of the primary coil 85 of the audio transformer 86, the opposite side of which coil 85 is connected by the conductor 87 to a positive terminal 88 of the Bbattery 38. The terminal 88 under the circumstances mentioned hereinabove is preferably of volts. The secondary coil 89 of the audio transformer 86 is connected at one side to the 'rid electrode 90 of the audion tube 91 an at its opposite side by the conductors 92, 80, 78, 66 and 40 to the negative terminal 39 of the B battery38 and jointly through the con ductor 41 to negative terminal 21 of the A battery 22. The filament electrode 93 of the audion 91 is connected on one sideby minal 30 of the A battery 22. The plate electrode 97 of the audion 91 is connected by the lead 98 to one terminal of the head phone 99, loud speaker or suitable sound' emitting device, the op osite" terminal of which is connected by t elead 100 to the terminal 88 of the B battery 38.

The above receiving system, as indicated any grid. leak such as is indicated at 110 or a grid ci'indenser as is indicated at 111.

The formation of the coils of the prin'iary of the radio couplings i l, 34, 56 may be as desired, but I prefer the formation of the windings and ti'irns thereof is set forth in my copending application Serial No.2,520

entitled Reactance coils-'and filed by me in the U. S. Patent Office on the 15th day of January, 1925.

In the embodiments of my invention as hereinabove described, it will be observed that the capacity reactance of the input circuit of each radio frequency stage is varied simultaneously with and in the same direction as the inductive reactance of the coupled output circuit of the antenna circuit and the radio frequency stages respectively. Thus, for example, when eachrotor coil is mounted on the shaft of its associated tuning condenser to be substantially concentric with the associated fixed secondary coil member and also substantially concentric with the associated fixed coil of the primary member when the rotor blades of such tuning condenser are in the position of maximum capacity of the tuning condenser, upon turning the dial of each tuning condenser for varying the capacity of the tuning con-' denser, aside from the Lin-essential interac tions which take place, the essential features effected by the present invention embody the variation of the self-induction of the primary circuit and also of the mutual induction of the associated transformer simultaneously with and in the same direction as the variation of the capacity of the circuit of the associated tuning condenser. It is my observation that such relationship electrically and mechanically of properly proportioned coils and associated tuning condensers attains the advantages of my invention herein set forth, and particularly in' eliminating substantially all objectionable feed-back oscillations.

If it is desired to interpose a form of my two circuit coil coupling between the aerial and the first radio frequency stage, such arrangement may be had as is indicated in Fig. 2 showing a detail diagram of the aerial circuit. the interposed circuit and the first radio frequency stage, wherein the parts in Fig. 2 corresponding to the parts of .Fig. 1 are designated by like reference numbers. It will be understood that the remainder of the receiving system for the next one or more radio frequency stages with the detector stage and one or more audio frequency stages is arranged in conformity to the circuit indicated in Fig. 1.

In Fig. 2 the aerial is indicated at 1, the circuit of which is connected through the fixed primary coil 101, thence through the rotor coil 102, conductor 103 to ground 12. The secondary ofthe coupling 10 1 is indicated at 105. The secondary 105 is connected at its opposite ends through the fixed primary coil- 4, rotor primary coil 8, thcncc by conductor 106, lead '107 to the-ground wire 108 and thence to gIOUI'lfllQ, The conductor 106 is connected by'thc lead 108 corcsponding to the lead 18 of the arrangement indicated in Fig/1. Y

Preferably, the rotor coil is connected in series with the fiiced coil of each primary member in the manner indicated in the drawings and as above described, and the relation of electrical connection of the rotor primary coil and the fixed primary coil may be varied as desired to attain the objects of my invention. Similarly, the primary coil may be of a single coil construction and the secondary coil of a plurality of coils one of which is movable and preferably rotatable for varying the inductive relation of the movable coil relative to the remaining coil or coils.

It will also be apparent that my invention is applicable for various types of radio receiving systems and various types of circuits, comprising at least one radio frequency stage and a detector stage.

Whereas I have described my invention in reference to specific forms thereof, it will be understoodthat many changes and modifications may be made without departing from the spirit of the invention.

I claim:

1. In a multi-stage transformer coupled, radio frequency system, means for varying the capacity reactance in each transformer secondary circuit, means for varying the self-inductance of each primary and the mutual inductance of each transformer, and means for mechanically coupling sai d firstnamed means with said second-named means to thereby vary each of said ireacta-nces simultaneously and in the same direction, said coils and said condensers being relatively so proportioned that iobjectionabile feed-back oscillations are substantially eliminated.

2. In a multi-stage transformer coupled, radio frequency system, each transformer comprising relatively fixed primary and secondary coil portions, each primary further including a relatively movable coil portion, a tuning condenser connected across the secondary of each radio frequency stage, and means for mechanically coupling each movable primary coil portion with its associated tuning condenser to thereby vary the self-inductance of each primary and the mutual inductance of each transformer simultaneously with and in the same direction as the variation of the capacity reactance of the circuit of the associated tuning condenser, said coils and said con" dcnsers being relatively soproportioned that objectionable feed-back oscillations are substantially eliminated.

3. In a multi-stage transformer coupled, radio frequency system, each-transformer comprising relatively fixed primary and secondary coil portions, each primary further including a relatively movable coil portion, a tuning condenser connected across the secondary of each radio frequency stage, and means for mounting each primary coil portion on the shaft of its associated tuning coil to thereby vary the self-inductance of each primary and the mutual inductance of each transformer simultaneously with and in the same direction as the variation of the capacity reactance of the circuit of the associated tuning condenser, salrl coils and said condensers being relatively so proportioned that objectionable feed-back os- -cillations are substantially eliminated.

In testimony whereof I have signed this specification this 6th day of March, 1925.

FRANCIS L. LORD. 

